Apparatus for controlling the alkalinity of ore pulp



Oct. 12, 1954 WALLACH 2,691,442

APPARATUS FOR CONTROLLING THE ALKALINITY OF ORE PULP Filed Jan. 27, 1951 3 Sheets-Sheet l F/Gl.

INVENTOR ALBERT A. WALLACH BY M z 7W Oct. 12, 1954 APPARATUS FOR Filed Jan. 27, 1951 A. A. WALLACH CONTROLLING THE ALKALINITY OF ORE PULP 5 Sheets-Sheet 2 INVENTOR ALBERT A. WALLAC H w M f Oct. 12, 1954 WALLACH 2,691,442

APPARATUS FOR CONTROLLING THE ALKALINITY OF ORE PULP Filed Jan. 27, 1951 3 Sheets-Sheet 3 INVENTOR ALBERT A. WALL AC H MMXM ATTOR NE Y Patented Oct. 12, 1954 UNITED STATES PATENT OFFICE APPARATUS FOR CONTROLLING THE ALKALINITY OF ORE PULP Claims.

This invention pertains to a method and apparatus for controlling the alkalinity of ore pulp, which is to be treated by the flotation process.

In handling sulphide ores it is necessary to control the alkalinity of the pulp to gain full efiiciency of the flotation re-agents. The general practice is to maintain alkalinity by adding lime, or a lime slurry to the ore before it enters the grinding mill. The attention of several persons is requried to make tests at intervals of time and to add lime or control the amount of slurry entering the mill as considered necessary. This method is costly, inaccurate, subject to human error and not consistent as to results.

One of the objects of my invention is to provide improved automatic means for controlling the alkalinity of the ground ores entering the flotation system.

Another object is to provide apparatus for automatically sampling groundore and for testing the samples at determined intervals and controlling apparatus for feeding lime to the crushed or ground ore before it enters the flotation portion of the mill. I

Another object is to provide apparatus for checking the sampling mechanism, or the limo feed control mechanism, and issuing a visible and audible warning in case operation of either is not properly operating.

Another object is to provide means for automatically checking quantitative samples taken at determined intervals of fluid filtered from ground ore, prior to its entry into the flotation system of the mill, by chemical and electronic means and for automatically varying the amount of lime added to the ore according to results obtained from such checks.

Another object is to provide apparatus, of the type described, in which the alkaline content of a measured sample is determined by photoelectric means, and wherein provision is made for the addition of a measured quantity of a standardized acid, together with an indicator, to the sample before measuring the light transmitting qualities of the mixture.

I attain the foregoing objects by means of the apparatus, construction and arrangement of parts, and method hereinafter described, illustrated in the accompanying drawings in which- Figure 1 is a diagrammatic representation of a mill arrangement to which the apparatus here concerned is applied; and

Figure 2 is a diagrammatic illustration of the combination of apparatus embodying my improved apparatus, and

Figure 3 is a perspective view of the photoelectric determination and checking mechanism and apparatus.

Similar numerals refer to similar parts in the several views.

The installation 01' the apparatus here concerned and its position in a concentration mill to which it is applicable is shown in general diagrammatically, in Figure 1. In this figure, 2 indicates the ore crusher, 3 the grinding mill, 4 the classifier, and 5 the flotation cells. The apparatus here concerned, 5, takes samples from ground ore pulp through filters 1 positioned just ahead of the flotation cells 5, and through means, hereinafter described, varies the addition of lime to crushed ore at position 8 where the crushed ore is fed into the grinding mill 3.

This arrangement, while generally followed, is subject to slight variations in certain installations for specific purposes.

Millrun ground pulp is filtered by apparatus generally known as siphon filters. These are indicated at 1, Figure l, and are preferably positioned ahead of the flotation cells 5. Clear filtrate from this apparatus constituting a representative sample of the fluid portion of the ground pulp enters a sample measuring vessel l 0, through sample tube I 2 continuously during operation. Overflow leaves this vessel through sample held tube I4. A sample discharge tube [6 leads from the bottom of vessel I 0 to a mixing and deter mination vessel ll positioned below it. This is made of clear glass or other transparent material and has parallel flat transparent sides l8. Flow through tube I2 is controlled by electrically operated valve 19. Flow through discharge tube I6 is controlled by a similarly constructed discharge valve 2|. A discharge tube 23 is positioned in the bottom of this vessel and is provided with electrically operated valve 24.

Overflow tube l4 leads to check vessel 26 which is of the same construction as determination and mixing vessel I1 and is disposed in horizontal and alined position therewith within case 40.

This vessel is provided with an overflow spout 43 so that a predetermined amount of filtrate will be contained therein at all times during normal and proper operation. A drain tube 31 opens into its bottom and is provided with manually operated valve 38.

A branch fitting 27 just below valve 2| connects tube It with an acid supply tube 28 which leads from an acid measuring container 30 Tube 28 is provided with an electrically operated valve 32. Acid container 30 is kept filled with a predetermined volume of a standard acid containing a small measured amount of color producing indicator, sensitive to alkali, such as phenolphthalein, by an electrically operated pump 34 which draws this acid mixture from a supply vessel 35, while excess fluid returns through overflow spout 36. The leads supplying current to electric pump 34 include a solenoid operated switch 33 which is, in turn, connected in parallel to conductors 31 which control the operation of valves [9, 2i and 32. Switch 33 is set to open when these valves operate. Pump 34 is therefore inoperative while container 30 drains into vessel l'l.

Spout 36 acts as a weir and is slidably adjustable vertically in the wall 39 between the acid container 32) and the mixture supply vessel 35. The level of the liquid in container 39 may be varied by raising or lowering spout 36 and thus the amount of acid introduced into the determining vessel varied accordingly.

A sample testing cabinet consisting of a light proof rectangular case 40, indicated by dotted outline Fig. 2, houses vessels H and 26. These vessels are preferably positioned in the same horizontal plane and are positioned in the end portions of the case. Vessel 25 is supported on one end of a balance beam M. The opposite end of this beam carries a balancing weight 45 and is adapted to operate an electrical switch 46 which closes when the weighted end of the beam descends, and opens when it is raised.

A photoelectric cell 48 is located at the end of the box 49 adjacent vessel ll. At the opposite end of the box, and adjacent vessel 25 there is a photoelectric cell 53. In the middle of box 43 there is an electric lamp 52 which is energized from a battery 54, kept charged so that light rays emitted from lamp 52 are of continuously uniform brilliance. It may be termed a constant source of light.

Lamp 52 is confined in a central compartment 53, the end walls of which have apertures 55 which direct light through filters 55 and so that the filtered rays travel through vessel ii at the right end of the case 40 and impinge upon photoelectric cell 48, and travel through vessel 26 at the left end of the case and impinge on photoelectric cell 50.

Filters 56 and 51 are preferably made of transparent material colored true green; that is, they are stained so as to transmit light of approximately 5500 Angstrom units. These filters filter out all rays except those which may be wholly or partially blocked by the red or pinkish color of phenolphthalein indicator when effected by alkali or base ions in solution in determination vessel ll, or vessel 26.

Operation of the lime control portion of the apparatus is controlled and timed at predetermined intervals by a timer switch 66 operated by clock mechanism 3|. Contact arm 53 of the switch makes electrical connections through the several contact terminals hereinafter mentioned, to operate various parts of the above mentioned apparatus at timed intervals.

Arcuate contact terminal 34 is connected to a source of power 66 and the electrically operative parts of valves 19, 2| and 32 and to solenoid switch 33. Annularly disposed from terminal (it is terminal 68 which is connected to vessel emptying valve 24.

A second arm 65 also operated by timer mechanism 6| contacts arcuate terminal 69 and these parts constitute a switch which is in circuit with the armature contacts of power relay l2 and motor 14. This switch determines the increment of time during which motor I4 will run when sensitive relay H! activates relay I2.

Photoelectric cell 48 is connected to the sensitive relay it which has an armature operating only a single contact. This relay controls a double contact power relay '12. This power relay is connected to motor '14 which has two oppositely wound field coils l5 and '15. Contact of armature of this relay with terminal 8! will energize field coil 15 and motor armature 82. Conversely, contact with terminal 33 will energize the oppositely wound field coil it as well as armature 32. Spring 84 maintains armature 8E1 normally in contact with terminal 83. This motor is mechanically connected to the valve stem of lime control valve 86 which controls the fiow of lime slurry from supply vat 81 to the location for mixing 8.

Photoelectric cell 50 is connected to sensitive relay 9i} and this, in turn to controls circuit 9| which includes a power source 92, a signal light 93, and an alarm horn 94.

Operation Clear filtrate to be sampled enters vessel in continuously from siphon filters '1. After the vessel is filled to a determined level it runs through overflow tube 14 to vessel 23. At intervals governed by timer switch 60, valve l9 closes and switch 33 opens and at the same time valves 2| and 22 are opened. The contents of vessels [0 and 38 are then mixed in tube l6 and flow into determination vessel IT. The contents of vessel 39 is a measured quantity of normal sulphuric acid and a small measured amount of phenolphthalein as an indicator. If the lime quantity in the sample is low, and not sufiicient to neutralize the acid introduced from vessel 3%, the solution in determination vessel 11 will remain clear. Light from lamp 52 will activate photoelectric cell 48; this will close relay HI and operate relay [2 so that contacts are made to cause motor M to turn in a direction to open lime valve 86. Conversely, if the lime or alkali content of the sample is high, and the measured quantity of acid does not neutralize it, the indicator will render the mixture in vessel I! pink or red and sufiiciently opaque to filtered rays from lamp 52 so as not to pass sufiicient light to sensitize photoelectric cell 48 to activate it. This causes relay it to remain open and armature 8B of relay i2 remains in contact with terminal 83 during the time timing switch 60 is closed. The increment of this operation is determined by the time switch 50.

After switch arm 63 leaves contact terminal 68 valves 2! and 32 close and valve [9 opens and switch 33 closes again. It is to be here noted that the lime slurry is added ahead of the position where the sample was taken, and an appreciable amount of time is consumed before the results of the increased amount of lime show in the samples where taken. Timing of the samples is determined accordingly.

The testing portion of the apparatus functions to mix a measured quantity of filtrate sample with a measured quantity of acid mixture containing a base or alkali sensitive indicator, at predetermined testing intervals, and to operate a lime control valve (or other lime supply apparatus) to give it either opening or closing motion depending on the alkalinity or acidity of said sample for a determined period of time during said testing intervals. It is obvious that instead of opening or closing a limit control valve 86, motor 14 could operate a rheostat which would control the speed of a lime slurry pump, or motor could be directly coupled to a lime slurry circulating pump in which case the double reversing fields l5 and 16 would be unnecessary.

The other (left hand) portion of the apparatus acts as a safety check on the functioning of the sampling apparatus and operation of the photoelectric unit. This checking apparatus includes the vessel 26 on balance beam 44, photoelectric cell 50, relay 90, and. the alarm apparatus 94 and 93.

This portion of the apparatus operates as follows:

Overflow of filtrate from vessel enters vessel 26 through tube l4. A determined quantity of filtrate is maintained in vessel 26 so long as a normal flow enters from the overflow of vessel H). Excess is drained oil by overflow spout 43 to maintain a predetermined level in the vessel. The weight of this determined quantity of filtrate in the vessel is balanced by weight 45 so that normally, when filtrate is flowing steadily through tube l4, switch 46 is open. Valve 38 in tube 31 is set to drain filtrate from vessel 26 at a slow predetermined rate so that, depending on the time intervals of the operation of the testing portion of the apparatus, filtrate will be drained from vessel 26 and its weight lessened in a determined time after normal flow through tube l4 ceases. In such an event vessel 26 loses weight, and the weighted end of beam 44 descends thus closing switch 46 which activates alarms 93 and 94. It is to be understood that filtrate is continuously supplied in an amount in excess of that required to keep vessels I 0 and 26 filled.

Secondly, if for any reason lamp 52 ceases to operate, or maintain sufficient predetermined brilliancy, photoelectric cell 50 will cease to be activated and, since this is connected to relay 80 to normally maintain it open, the relay switch will close and activates alarms 93 and :94.

Thirdly, in case the filters through which the flow through tube 14 is obtained fail and the solution in vessel 26 does not remain clear, then the light supplied cell 50 will be insufficient to maintain relay 90 open and it will close and sound the alarms. It may, under some circum-- stances, be desirable to adjust filter 51 to secure the best results for this particular purpose.

By this portion of the apparatus, therefore, both the quantity and quality of the filtrate is checked, as well as the brilliance of lamp 52 which is the activating light source of the testing portion of the apparatus.

I claim:

1. In lime control apparatus of the type herein described including a siphon filter drawing clear filtrate for sampling from ground ore pulp, a lime slurry supply, a lime slurry supply pipe leading from said slurry supply to an ore pulp chute carrying ore pulp to which lime is to be added when necessary to maintain alkalinity, a, lime control valve in said pipe, and a reversible electric motor operating said valve; apparatus for sampling the alkalinity of said filtrate taken from said ore pulp at determined intervals and for varying the amount of lime slurry added to said ore pulp in said chute through said lime supply pipe at corresponding intervals by opening or closing movement of said lime control valve including a filtrate supply pipe having a normally open electrically operated sample supply valve; a sample measuring vessel receiving a flow of filtrate from said siphon filters through said supply pipe, having an overflow pipe near its top to determine a measured sample of filtrate in said vessel, and a discharge tube in its bottom provided with a normally closed electrically operated discharge valve; a mixing and determining vessel of transparent material arranged to receive the measured contents of said measuring vessel at predetermined intervals of time through said discharge tube; an emptying tube in the bottom of said mixing and determinin vessel provided with a normally closed electrically operated emptying valve; an acid measuring vessel holding a measured amount of standardized acid mixed with a determined amount of color responsive alkali indicator; and having a discharge tube in its bottom dispo s ed to discharge its contents into said measuring and determining vessel provided with a normally closed electrically operated valve; a sample taking electric timer switch operating said electrically operated valves, at predetermined intervals of time, arranged to shut off filtrate fiow to said measuring vessel by closing said valve in said filtrate supply pipe, to empty the contents of said measuring vessel into said mixing and determining vessel by opening the valve in said measuring vessel discharge tube; to empty the measured amount of acid and indicator into said mixing and determining vessel by opening the valve in the discharge tube of said vessel and thereafter, following a timed interval, emptying said mixing and determining vessel by opening the valve in the discharge tube in the bottom of said vessel, and restoring said other valves, above mentioned, to normal position; an electric lamp directing a beam of light through said mixing and determinmg vessel; a photo-electric cell disposed to receive said beam of light passing through said mixing and determining vessel and arranged to be electrically responsive thereto; electrical apparatus, including a timer switch coordinated with said sample taking timer switch, connected to said photoelectric cell to be controlled thereby, and connected to said reversible lime slurry valve motor to control the operation thereof, arranged to operate said motor to provide opening movement of said valve when light passes through said mixed solutions in said mixing and determining vessel and actuates said cell, and to provide closlllgmovement for said lime slurry valve when the passage of light to said cell is impeded by opaqueness of said mixed solutions caused by the action of said alkalinity indicator.

2. In lime control apparatus of the type herein described including a siphon filter drawing clear filtrate for sampling from ground ore pulp, a lime slurry supply, a lime slurry supply pipe leading from said slurry supply to an ore pulp chute carrying ore pulp to which lime is to be added when necessary to maintain alkalinity, a lime control valve in said pipe, and a reversible electric motor operating said valve; apparatus for sampling the alkalinity of said filtrate taken from said ore pulp at determined intervals and for varying the amount of lime slurry added to said ore pulp in said chute through said hmesupply pipe at correspondin intervals by opening or closing movement of said lime control valve including a filtrate supply pipe having a normally open electrically operated sample supply valve; a sample measuring vessel receiving a flow of filtrate from said siphon filters through said supply pipe, having an overflow pipe near its top to determine a measured sample of filtrate in said vessel, and a discharge tube in its bottom provided with a normally closed electrically operated discharge valve; a mixing and determining vessel of transparent material arranged to receive the measured contents of said measuring vessel at predetermined intervals of time through said discharge tube; an emptying tube in the bottom of said mixing and determining vessel provided with a normally closed electrically operated emptying valve; an acid measuring vessel holding a measured amount of standardized acid mixed With a determined amount of color responsive alkali in dicator; and havin a discharge tube in its bottom disposed to discharge its contents into said measuring and determining vessel provided with a normally closed electrically operated valve; a sample taking electric timer switch operating said electrically operated valves, at predetermined intervals of time, arranged to shut off filtrate fiow to said measuring vessel by closing said valve in said filtrate supply pipe, to empty the contents of said measuring vessel into said mixing and determining vessel by openingthe valve in said measuring vessel discharge tube, to empty the measured amount of acid and indicator into said mixing and determining vessel by opening the valve in the discharge tube of said vessel and thereafter, following a timed interval, emptying said mixing and determining vessel by opening the valve in the discharge tube in the bottom of said vessel, and restoring said other valves, above mentioned, to normal position; an electric lamp directing a beam of light through said mixing and determining vessel; a photo-electric cell disposed to receive said beam of light passing through said mixing and determining vessel and arranged to be electrically responsive thereto; electrical apparatus, including a timer switch coordinated with said sample taking timer switch, connected to said photoelectric cell to be controlled thereby, and connected to said reversible lime slurry valve motor to control the operation thereof, arranged to operate said motor to provide opening movement of said valve when light passes through said mixed solutions in said mixing and determining vessel and actuates said cell, and to provide closing movement for said lime slurry valve when the passage of light to said cell is impeded by opaqueness of said mixed solutions caused by the action of said alkalinity indicator; and alarm apparatus sensitive to the flow of filtrate from said siphon filters through said sample measuring vessel, and sensitive to the intensity of light emitted by said electric light and to the transparency of said filtrate, including a transparent overflow vessel, receivingpredetermined normal overflow from said measuring vessel and having an overflow at its top, and a drain tube in its bottom draining off filtrate at a determined rate less than said normal predetermined flow; a balancing beam supporting said overflow vessel on one end and counterbalanced at the other end to maintain said vessel in a lowered position when it is receiving said normal predetermined fiow of said filtrate from said measuring vessel and energizing an alarm when said overflow vessel is lightened by receiving less than normal flow; a photo-electric cell disposed relative to said electric lamp to receive light therefrom through said overflow vessel, connected to electrical alarm apparatus operated by an electrical switch normally open when said photo-electric cell is receiving a predetermined amount of light from said electric lamp through said vessel, and closing and sounding said alarm when said electric lamp dims, and

when light passing through said vessel is impeded by cloudiness of filtrate in said vessel.

3. In lime control apparatus of the type herein described including a siphon filter drawing clear filtrate for sampling from ground ore pulp, a lime slurry supply, a lime slurry supply pipe leading from said slurry supply to an ore pulp chute carrying ore pulp to which lime is to be added when necessary to maintain alkalinity, a lime control valve in said pipe, and a reversible electric motor operating said valve; apparatus for sampling the alkalinity of said filtrate taken from said ore pulp at determined intervals and for varying the amount of lime slurry added to said ore pulp in said chute through said lime supply pipe at corresponding intervals by opening or closing movement of said lime control valve including a filtrate supply pipe having a normally open electrically operated sample supply valve; a sample measuring vessel receiving a flow of filtrate from said siphon filters through said supply pipe, having an overflow pipe near its top to determine a measured sample of filtrate in said vessel, and a discharge tube in its bottom provided with an electrically operated discharge valve; a mixing and determining vessel of transparent material arranged to receive the con tents of said measuring vessel at predetermined intervals of time through said discharge tube; an emptying tube in the bottom of said mixing and determining vessel provided with an electrically operated emptying valve; an acid measuring vessel holding a measured amount of standardized acid mixed with a determined amount of color responsive alkali indicator, and having a discharge tube in its bottom leading to said determining vessel provided with an electrically operated valve; a sample taking electric timer switch operating said electrically operated valves, at predetermined intervals of time, shutting off filtrate flow to said measuring vessel by closing said valve in said filtrate supply pipe, and emptying the contents of said measuring vessel into said mixing and determining vessel by opening the valve in said measuring vessel discharge tube, and emptying the measured amount of acid and indicator into said mixing and determining vessel by opening the valve in the discharge tube of said vessel, and thereafter, after a timed interval, emptying said mixing and determining vessel by opening the valve in the discharge tube in the bottom of said vessel; a light source composed of an electric lamp directing a beam of light through said mixing and determining vessel; a photo-electric cell disposed to receive said beam of light pass in through said mixing and determining vessel being electrically responsive thereto; electrical apparatus, including a timer switch coordinated with said sample taking timer switch, connected to said photo-electric cell and controlled thereby, connected to said reversible lime slurry valve motor and controlling the operation thereof, so that said motor operates to open said valve when light passes through said mixed solutions in said mixing and determining vessel and actuates said cell during a timed interval, and operates to close said lime slurry valve during a timed interval when the passage or light to said cell is impeded by opaqueness of said mixed solutions caused by the action of said alkalinity indicator.

4. In ore treatment machinery, including a pulp conveyor, grinder and a lime slurry supply pipe adapted to add lime slurry to pulp passing through said pulp conveyor prior to its entry into said grinder, apparatus for controlling the alkalinity of said ore pulp in said conveyor prior to entrance of said pulp into said grinder consisting of siphon filters drawing clear filtrate from said ore pulp in said conveyor for sampling; a filtrate supply tube connecting said siphon filters with a sample measuring vessel having an electrically operated shutoff valve; a sample measuring vessel having an over-flow tube near its top to maintain a predetermined quantity of filtrate therein, and a discharge tube at its bottom provided with an electrically operated shutoff valve; a mixing and determining vessel of transparent material disposed below said sample measuring vessel adapted to receive measured quantities of filtrate from said sample measuring vessel through the discharge tube at the bottom of said vessel; a drain tube in the bottom of said mixing and determination vessel provided with an electrically operated shutoff valve; an acid measuring vessel holding a determined quantity of acid of predetermined strength containing a predetermined quantity of color producing indicator sensitive to alkali disposed above said mixing and determining vessel, and having an acid supply tube at its bottom provided with an electrically operated shutoff valve, connecting to said mixing and determining vessel; an electric timing switch having a first contactor connected in circuit with a source of power and said filtrate shutoff valve, and with the valve in said discharge tube of said measuring vessel, and with the valve in the acid supply tube in the bottom of said acid measuring vessel; a second cont actor adapted to open the valve in the drain tube in the bottom of said mixing and determination vessel a predetermined time after said mixing and determination vessel has been filled; means for determining the alkalinity of mixed solutions of filtrate sample and acid and indicator solutions in said mixing and determination vessel including an electric lamp as a light source directing a beam of light rays through the transparent walls of said mixing and determination vessel; a photo-electric cell receiving a beam of said light rays from said light source after said beam of light has passed through said mixing and determination vessel; an apparatus for controlling the flow of lime slurry into said ore pulp in said conveyor including a regulating valve in said lime slurry supply pipe, a reversible motor adapted to operate said valve, a time switch operating said motor controlling said valve at predetermined intervals of time coordinated with said sample determining timing switch; means for controlling the direction of the operation of said motor composed of a double contact power relay connected to energize said reversible motor; a sensitive relay connected to said photo-electric cell; electric connections between said cell, said sensitive relay and a power relay arranged so that when the mixed solution in said mixing and determining vessel remains clear said motor will operate to tend to open said lime slurry regulating valve during the timed operating interval of said motor, and when said indicator colors said solution due to the presence of alkali in excess of an amount suflicient to neutralize the acid solution added to said sample solution in said mixin and determination vessel, said motor will operate to tend to close said regulating valve during said timed operating in terval.

I 5. In apparatus as described in claim 1 the combination therewith of automatic operation checking apparatus consisting of a turbidity checking vessel of transparent material receiving filtrate from the overflow from said measuring vessel and having an overflow near its top and outlet at the bottom drawing off filtrate at a rate less than the rate of inflow from said measuring vessel to maintain said vessel filled to the level of its said overflow so long as a predetermined fiow from said sample measuring vessel is maintained; a balancing beam supporting said turbidity checking vessel, counterbalanced to maintain said vessel in a lowered position so long as said vessel is filled to the level of said overflow and raise to alarm operating position when said vessel is less than filled; an electrical alarm operating switch connected to said beam and energizing said alarm when said vessel raises above said lowered position; a checking photo-electric cell disposed to receive light from the said electric lamp associated with the said photo-electric cell controlling operation of said lime slurry valve through said turbidity checking vessel, connected through electrical circuits to alarm apparatus and energizing said alarm apparatus when light received from said lamp through said vessel diminishes below a predetermined brilliance.

Engineering and Mining Journal, vol. 148, No.

11, November 1947, pages 139, 142-144; McGraw-- Hill Pub. 00., N. Y. Copy in S. L.

Taggart: Handbook of Mineral Dressing, J. Wiley & Sons, N. Y., 1945, pp. 2-67, Sec. 2. Copy in Div. 55.

Applications of Photo-electric cell to Chemical Analysis and Control, Partridge, pp. 207-213, Industrial and Engineering Chem, July 1930. 

1. IN LIME CONTROL APPARATUS OF THE TYPE HEREIN DISCRIBED INCLUDING A SIPHON FILTER DRAWING CLEAR FILTRATE FOR SAMPLING FROM GROUND ORE PULP, A LIME SLURRY SUPPLY, A LIME SLURRY SUPPLY PIPE LEADING FROM SAID SLURRY TO AN ORE PULP CHUTE CARRYING ORE PULP TO WHICH LIME IS TO BE ADDED WHEN NECESSARY TO MAINTAIN ALKALINITY, A LINE CONTROL VALVE IN SAID PIPE, AND A REVERSIBLE ELECTRIC MOTOR OPERATIANG SAID VALVE; APPARATUS FOR SAMPLING THE ALKALINITY OF SAID FILTRATE TAKEN FROM SAID ORE PULP AT DETERMINED INTERVALS AND FOR VARYING THE AMOUNT OF LIME SLURRY ADDED TO SAID ORE PULP IN SAID CHUTE THROUGH SAID LIME SUPPLY PIPE AT CORRESPONDING INTERVALS BY OPENING OR CLOSING MOVEMENT OF SAID LIME CONTROL VALVE INCLUDING A FILTRATE SUPPLY PIPE HAVING A NORMALLY OPEN ELECTICALLY OPERATED SAMPLE SUPPLY VALVE; A SAMPLE MEASURING VESSEL RECEIVING A FLOW OF FILTRATE FROM SAID SIPHON FILTERS THROUGH SAID LIME SUPPLY PIPE AT CORAN OVERFLOW PIPE NEAR ITS TOP TO DETERMINE A MEASURED SAMPLE OF FILTRATE IN SAID VESSEL, AND A NORMALLY CLOSED ELECTRICALLY OPERATED DISCHARGE VALVE; CHARGE TUBE IN ITS BOTTOM PROVIDED WITH A NORA MIXING AND DETERMINING VESSEL OF TRANSPARENT MATERIAL ARRANGED TO RECEIVE THE MEASURED CONTENTS OF SAID MEASURING VESSEL AT PREDETERMINED INTERVALS OF TIME THROUGH SAID DISCHARGE TUBE; AN EMPTYING TUBE IN THE BOTTOM OF SAID MIXING AND DETERMINING VESSEL PROVIDED WITH A NORMALLY CLOSED ELECTRICALLY OPERATED EMPTYING VALVE; AN ACID MEASURING VESSEL HOLDING A MEASURED AMOUNT OF STANDARIDIZED ACID MIXED WITH A DETERMINED AMOUNT OF COLOR RESPONSIVE ALKALI INDICATOR; AND HAVING A DISCARGE TUBE IN ITS BOTTOM DISPOSED TO DISCHARGE ITS CONTENTS INTO SAID MEASURING AND DETERMINING VESSEL PROVIDED WITH A NORMALLY CLOSED ELECTRICALLY OPERATED VALVE; A SAMPLE TAKING ELECTRIC TIMER SWITCH OPERATING SAID ELECTRICALLY OPERATED VALVES, AT PREDETERMINED INTERVALS OF TIME, ARRANGED TO SHUT OFF FILTRATE FLOW TO SAID MEASURING VESSEL BY CLOSING SAID VALVE IN SAID FILTRATE SUPPLY PIPE, TO EMPTY THE CONTENTS OF SAID MEASURING VESSEL INTO SAID MIXING AND DETERMINING VESSEL BY OPENING THE VALVE IN SAID MEASURING VESSEL DISCHARGE TUBE; TO EMPTY THE MEASURED AMOUNT OF ACID AND INDICATOR INTO SAID MIXING AND DETERMINING VESSEL BY OPENING THE VALVE IN THE DISCHARGE TUBE OF SAID VESSEL AND THEREAFTER, FOLLOWING A TIMED INTERVAL, EMPTYING SAID MIXING AND DETERMINING BY OPENING THE VALVE IN THE DISCHARGE TUBE IN THE BOTTOM OF SAID VESSEL, AND RESTORING SAID OTHER VALVES, ABOVE MENTIONED, TO NORMAL POSITION; AN ELECTRIC LAMP DIRECTING A BEAM OF LIGHT THROUGH SAID MIXING AND DETERMINING VESSEL; A PHOTO-ELECTRIC CELL DISPOSED TO RECEIVE SAID BEAM OF LIGHT PASSING THROUGH SAID MIXING AND DETERMINING VESSEL AND ARRANGED TO BE ELECTRICALLY RESPONSIVE THERETO; ELECTRICAL APPARATUS, INCLUDING A TIMER THERETO; ELECTRICAL APPARATUS SAMPLE TAKING TIMER SWITCH, COORDINATED WITH SAID PHOTOELECTRIC CELL TO BE CONNECTED TO SAID CONNECTED TO SAID REVERSIBLE LIME SLURRY VALVE MOTOR TO CONTROL THE OPERATION THEREOF, ARRANGED TO OPERATE SAID MOTOR TO PROVIDE OPENING MOVEMEMT OF SAID VALVE WHEN LIGHT PASSES THROUGH SAID MIXED SOLUTIONS IN SAID MIXING AND DETERMINING VESSEL AND ACTUATES SAID CELL, AND TO PROVIDE CLOSING MOVEMENT FOR SAID LIME SLURRY VALVE WHEN THE PASSAGE OF LIGHT TO SAID CELL IS IMPEDED BY OPAQUENESS OF SAID MIXED SOLUTIONS CAUSED BY THE ACTION OF SAID ALKALINITY INDICATOR. 